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SUMMARY:Melting in the deep mantle - Shun-ichiro  Karato (Yale University)
DTSTART:20160608T134500Z
DTEND:20160608T143000Z
UID:TALK66391@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Melting in the shallow mantle is well documented. It is caused
  by the adiabatic ascent of a material or by the addition of &ldquo\;flux&
 rdquo\; such as water and/or carbon dioxide that reduces the solidus. Melt
  density and melt morphology (i.e.\, the dihedral angle) are well known. C
 onsequently\, it is possible to interpret some geophysical observations in
  terms of the presence of melt: in most cases\, geophysical anomalies are 
 difficult to attribute to the presence of melt unless the melt geometry is
  unusual (e.g.\, zero dihedral angle).  <span>&nbsp\;&nbsp\;&nbsp\;&nbsp\;
 &nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\;&nbsp\; <br>Melting can also occ
 ur in the deep mantle particularly across the mantle transition zone and i
 n the D&rdquo\; layer. Recent experimental studies show that melting is ub
 iquitous in the deep mantle (deep upper mantle and the lower mantle)\, but
  the geochemical and geophysical consequence of melting in the deep mantle
  is largely unknown. In most cases\, melting in the deep mantle is &ldquo\
 ;flux melting&rdquo\; assisted by the volatiles. I will summarize the curr
 ent status of studies on melting in the deep mantle with the focus on the 
 conditions for melting\, chemical composition of the melt and the melt den
 sity with the focus on the role of water. Water-induced melting in the low
 er mantle is extensive and in almost all areas in the lower mantle melting
  is difficult to avoid unless other materials that dissolve volatiles exis
 ts (e.g.\, metallic Fe). The composition of the melt produced in the lower
  mantle is (Mg\,Fe)O-rich as opposed to the melt produced in the shallow m
 antle (SiO2-rich). Consequently\, the deep mantle melting will affect the 
 chemical evolution of Earth quite differently than the shallow mantle melt
 ing. However\, two key parameters\, namely the density and the dihedral an
 gle\, are poorly constrained. A review of current status and a discussion 
 on the future directions will be provided.</span>      <br>
LOCATION:Seminar Room 1\, Newton Institute
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